ITTO960289A1 - SUPPORTED FIBROUS FABRIC GROUP. - Google Patents

Description

DESCRIPTION of the industrial invention entitled: "Supported fibrous tissue group".

TECHNICAL FIELD OF THE INVENTION The present invention relates to a group of supported fibrous tissue, i.e., a fibrous tissue which adheres to a support material. The present invention also relates to a process for the preparation of such a group of supported fibrous tissue, as well as to processes for using such a group of supported fibrous tissue.

BACKGROUND OF THE INVENTION

For many years, filter media have been used to filter fine particles from fluids, especially liquids. Such filter media are available in a multitude of materials to meet particular filtering needs. Fibrous fabrics, such as those disclosed in U.S. Patent 4021281, are particularly suitable for filtering certain particulate materials from fluids.

Fibrous tissues possess the ability to remove some particles but unfortunately suffer from a lack of mechanical strength, for example, they deform easily. Consequently, a support material is often coupled to such fibrous tissue to provide a filter medium with satisfactory mechanical characteristics. This is especially true if the filter medium is used in pulsed flow or high shear environments or is subjected to high back flow pressures.

Many attempts have been made. of coupling of fibrous tissues to suitable support materials. These attempts have included injecting molten fibrous fabric directly onto a support material, thermal laminating a fibrous fabric directly onto a support material, and using an adhesive to attach a fibrous material to a support material. support. Each of these techniques is not without problems, such as low support-fibrous tissue adhesion, significant blocking of the pores of the fibrous tissue and / or support material, alteration of the physical characteristics of the fibrous tissue, and the introduction of possible sources of contamination.

Thus, there remains a need for a method of adhering a fibrous material to the surface of a support material, in particular a rigid support material, which method provides secure adhesion of the fibrous tissue to the support material without affecting in substantially negatively either the fibrous tissue or the support material. The present invention seeks to provide such a process and the resulting supported fibrous tissue group. These and other objects and advantages of the present invention, as well as additive features of the invention, will become apparent from the description described herein.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a supported fibrous fabric assembly comprising a support material which adheres to a multi-component fiber nonwoven fabric. The multicomponent fibers comprise a first polymer and a second polymer such that the second polymer is present on at least a portion of the surface of the multicomponent fibers and has a softening temperature lower than the softening temperatures of the first polymer and the support material. The supported fibrous fabric assembly has a water flow rate of at least about 20% of the water flow rate of the multicomponent fiber nonwoven fabric alone. The supported fibrous fabric assembly of the present invention may further comprise a second fibrous fabric which adheres to the multicomponent fiber nonwoven so as to position the multicomponent fiber nonwoven between the second fibrous fabric and the support material, and in wherein the supported fibrous tissue group has a water flow rate equal to at least about 20% of the water flow rate of the second fibrous tissue alone. The present invention also provides a filter element that includes a casing such as a supported fibrous tissue group, as well as a method for preparing such a supported fibrous tissue group and methods for using such a supported fibrous tissue group.

DESCRIPTION OF THE PREFERRED FORMS OF IMPLEMENTATION

The supported fibrous fabric group of the present invention comprises a support material which adheres to a nonwoven fabric of multicomponent fibers in which the multicomponent fibers comprise a first polymer and a second polymer such that the second polymer is present on at least a portion of the surface of the multicomponent fibers and has a softening temperature lower than the softening temperatures of the first polymer and the support material, and the supported fibrous tissue group has a water flow rate equal to at least 20% of the water flow rate of the non-woven fiber multicomponent alone. The supported fibrous tissue assembly may further comprise a second fibrous tissue which adheres to the multicomponent fiber nonwoven such that the multicomponent fiber nonwoven is positioned between the second fibrous tissue and the support material, and in which the supported fibrous tissue group has a water flow rate equal to at least 20% of the water flow rate of the second fibrous tissue alone.

Multicomponent fiber non-woven fabric

The multicomponent fiber nonwoven fabric can comprise any adequate amount of the first and second polymers such that the second polymer is present on at least a portion of the surface of the multicomponent fibers and has a softening temperature lower than the softening temperatures of the first polymer, the second fibrous tissue (if present), and the support material. Typically, multicomponent fibers comprise at least about 10% by weight of the first polymer having a first softening temperature and not more than about 90% by weight of a second polymer having a second softening temperature lower than the first softening temperature. , as well as the softening temperatures of the second fibrous material (if any) and support material. The multicomponent fibers preferably comprise at least about 30% by weight, more preferably at least about 40% by weight (e.g., about 40-60% by weight), of the first polymer and not more than about 70% by weight, plus preferably no more than about 60% by weight (e.g., about 60-40% by weight) of the second polymer. The multicomponent fibers preferably comprise a core of the first polymer and a cover which at least partially surrounds the surface of the second polymer. More preferably, the multicomponent fibers comprise a core of the first polymer and a cover of the second polymer (i.e., the second polymer forms a continuous cover on the surface of the core of the first polymer).

The multicomponent fibers of the non-woven fabric can be prepared with any suitable polymer. Preferably, at least the second polymer, and more preferably also the first polymer, are thermoplastic polymers. More preferably, the multicomponent fibers of the non-woven fabric will be prepared with suitable polyolefins. Suitable polyolefins include polyester, polyethylene, polypropylene, and polymethylpentene. The first polymer is preferably polyester, while the second polymer preferably is polyethylene. The multi-component fibers of the nonwoven fabric can be prepared by any suitable means and molded into the nonwoven fabric by any suitable means, such as conventional Fuordrinier papermaking processes. While multicomponent fibers are preferably bicomponent fibers, i.e., fibers prepared with only two polymers, multicomponent fibers can be prepared with more than two polymers, i.e., the first and / or second polymers described herein can be thought of as blends of polymers. The multi-component fiber may also comprise a suitable adhesion promoter, for example, a silane coupling agent, particularly when the support material is a metal, for example, stainless steel.

The particular combination of polymers of the multicomponent fibers should be chosen such that the softening temperatures of the first and second polymers differ sufficiently so that the softening of the second polymer can be carried out without adversely affecting the first polymer. , as well as the second fibrous tissue (if any) and support material. Thus, the first polymer, the second fibrous fabric (if present), and support material preferably have softening temperatures of at least about 20 ° C higher, more preferably at least about 50 ° C higher, than the softening temperature of the second polymer. The second polymer will typically have a softening temperature of about 110 ° C to about 200 ° C, more typically about 110 ° C to about 150 ° C. While the melting temperatures of the second fibrous fabric (if any), support material, and first and second polymers of the multicomponent fiber nonwoven fabric can be considered, the softening temperatures provide a more practical measure of the temperatures at which it can occur. deformation and / or flow of molten material of the various elements of the supported fibrous tissue group of the present invention.

The multicomponent fibers used to make the non-woven fabric typically have an average diameter of about 50 μm or less. More preferably, at least 90%, more preferably substantially all, of the multicomponent fibers which form the non-woven fabric will have a diameter of approximately 50 μιη or less. The multicomponent fibers that form the non-woven fabric will have a diameter typically comprised between 5 and 50 μm, more usually about 10-30 μπι. The multicomponent fibers can have any suitable length, for example, about 0.5-8 cm.

The multicomponent fiber nonwoven fabric can have any suitable sheet (or base) weight. The multicomponent fiber non-woven fabric preferably has a sheet weight of at least about 20 g / m2, more preferably between about 20 g / m2 and about 100 g / m2.

The multicomponent fiber nonwoven fabric can be of any suitable thickness and will generally be at least about 50 μm thick. The multicomponent fiber nonwoven fabric is preferably thick enough to provide the desired tear strength to the supported fibrous fabric group. Additionally, the multi-component nonwoven fiber should be thick enough to provide the desired physical separation between the second fibrous tissue when present and the backing material to allow sufficient lateral flow (e.g., edge or side flow. ) through the multi-component fiber nonwoven fabric, thus minimizing the pressure drop on the supported fibrous fabric group. The multicomponent fiber nonwoven fabric preferably has a thickness of less than about 5000 μm, more preferably less than about 2500 μm, and more preferably about 50 to about 1000 μm.

Multicomponent non-woven fiber fabric should be as uniform as possible in thickness. Preferably, the multicomponent fiber nonwoven fabric will have a thickness variability of not more than about ± 10%, more preferably not more than about ± 9%, which represents about 3 standard deviations of the mean thickness of the nonwoven fabric. More preferably, the multicomponent fiber nonwoven fabric will exhibit a thickness variability of no more than about 5%.

The multi-component non-woven fiber fabric can have any air permeability. Typically, the multicomponent fiber nonwoven fabric will exhibit an air permeability of about 30,000 to about 500,000 lpm / m2. The multicomponent fiber non-woven fabric preferably has an air permeability of about 100,000 to about 300,000 lpm / m2.

Support material

The support material can be any suitable material, desirably a material that is stiffer than the multi-component fiber nonwoven and the second fibrous material (if any). The support material desirably exhibits a stiffness in bending (cantilever test ASTM D 1388-64 (reapproved in 1975; editorial changes in 1975 and 1976)) of at least about 10 times, preferably at least about 50 times, more preferably at least about 100 times , for example, about 500 times or more, and more preferably at least about 1000 times, the flexural stiffness of the multicomponent fiber nonwoven fabric and the second fibrous fabric (if any). The support material also preferably has a tensile strength of at least 5 times, and more preferably at least about 10 times, the tensile strength of the multicomponent fiber non-woven fabric and the second fibrous fabric (if any). Also, the softening temperature of the support material should be higher than the softening temperature of the second multi-component fiber polymer.

The support material will typically be a polymeric material or a metal. Suitable polymeric materials include polyamide (e.g. nylon), polypropylene, polyethersulfone (PES), polysulfone (PSO), polythermide (PEI), polyetheretherketone (PEEK), and polyetheretherketone (PEK). Suitable metallic materials include metals, such as aluminum, and alloys such as stainless steel. The support material can take any suitable form, for example, sheet, fibrous, mesh, and the like.

The support material can be porous, such that the filtered fluid flows through the support material, or non-porous, such that the filtered fluid flows laterally through the multi-component fiber nonwoven, for example, between the second fibrous tissue (if any) and the support material. The support material is preferably porous, in particular a porous sheet of stainless steel, for example with chemically etched holes passing through it.

The support material can be made more suitable for adhesion to multi-component fiber nonwoven by roughening the surface of the support material. For example, the support material, particularly where it is a metal such as stainless steel, can be made more suitable for adhesion to the multi-component fiber non-woven fabric by etching and / or subjecting the material to heat treatment or otherwise. oxidative surface treatment.

Second fibrous tissue

The fibrous fabric group of the present invention may comprise a second fibrous fabric, i.e., a fabric of fibers in addition to the non-woven fabric of multicomponent fibers. Any suitable non-woven fibrous tissue can be used as the second fibrous tissue.

The second fibrous tissue can comprise any suitable material and can have any suitable embodiment. The second fibrous fabric can comprise multi-component fibers or single-component fibers and, thus, can be the same or different from the non-woven fabric of multi-component fibers. The second fibrous fabric preferably comprises single component fibers. The second fibrous fabric may have the hole of a non-woven fibrous fabric or a woven fibrous fabric (which includes meshes or filters), preferably a non-woven fibrous fabric.

Generally, when a second fibrous web is used, it will be the primary filter medium, while the multi-component fiber nonwoven fabric constitutes the means of adhesion of the second fibrous web to the support material.

Assembly procedure

The adhesion of the multicomponent fiber nonwoven fabric to the support material and the second fibrous fabric (if present) is achieved by subjecting the multicomponent fiber nonwoven fabric to a temperature higher than the softening temperature of the second polymer but lower than the softening temperatures of the first polymer, of the second fibrous tissue (if present), and of the support material. In other words, the multicomponent fiber non-woven fabric is subjected to a temperature sufficient for at least partial softening of the second polymer without significantly softening the other components of the supported fibrous fabric group so that the second polymer can melt so that the sufficient to achieve the achievable adhesion between the non-woven fabric of multicomponent fibers and the second fibrous fabric (if present) and support material.

Thus, the present invention provides a process for preparing a supported fibrous tissue group, wherein the process comprises (a) placing a multi-component fiber non-woven fabric in contact with a support material to make a group of supported fibrous tissue, wherein the multicomponent fibers comprise a first polymer and a second polymer such that the second polymer is present on at least a portion of the surface of the multicomponent fibers and has a softening temperature lower than the softening temperatures of the first polymer and the support material, (b) subjecting the multi-component fiber nonwoven fabric to a temperature above the softening temperature of the second polymer and below the softening temperatures of the first polymer and the support material, and (c) applying pressure to the group of fibrous tissue supported while the tissue does not te The fabric of multicomponent fibers is at a temperature higher than the softening temperature of the second polymer so that the support material adheres to the fabric of multicomponent fibers, and the group of supported fibrous fabric has a water flow rate equal to at least about 20 % of water flow rate of multicomponent fiber nonwoven fabric alone.

The process of the present invention may further comprise positioning the multi-component fiber non-woven fabric between the support material and a second fibrous fabric, subjecting the multi-component fiber non-woven fabric to a temperature higher than the softening temperature of the second polymer and lower than softening temperatures of the first polymer, second fibrous tissue, and support material and applying pressure to the supported fibrous tissue group while the multicomponent fiber nonwoven is at a temperature above the softening temperature of the second polymer such that the support material and the second fibrous web adhere to the multicomponent fiber nonwoven fabric, and the supported fibrous fabric group has a water flow rate of at least about 20% of the water flow rate of the second fibrous web alone.

The multicomponent fiber nonwoven fabric can be subjected to the desired softening temperature by any suitable means, including, but not limited to, hot plates, induction, microwaves, radio frequencies, convection, and the like. For example, the assembly of the present invention can be placed in an oven or on a hot plate or, more preferably, slid through interstices between heated rollers and / or between heated conveyor belts, until a desirable level of adhesion is obtained, for for example, tear strength, between the layers of the group without undesirable blocking or clogging of the pores. Similarly, a portion of the group can be brought to the desired temperature and then combined with the remaining portion (s) of the group.

More preferably, heat is applied to the assembly for a period sufficient for the multicomponent fiber nonwoven fabric to reach equilibrium at the desired temperature. The duration of such heating will depend in part on the heat application process and the precise physical characteristics of the group members.

While the multicomponent fiber nonwoven fabric is at an elevated temperature, i.e., at a temperature above the softening temperature of the second polymer, the assembly is preferably subjected to the application of an adequate amount of pressure which can be accomplished in any suitable manner. , for example, by means of interstice rollers and the like. The amount of pressure applied to the heated assembly necessary to obtain a good adhesion of the various components of the assembly will similarly vary according to the precise process that is used to achieve the adhesion of the components of the assembly and the physical nature of those components. Generally, an applied pressure of about 5-1500 kPa will suffice, with a more typically used applied pressure of about 10-1000 kPa.

It will be necessary to apply pressure for a time sufficient to allow the second polymer of the multicomponent fibers that form the multicomponent fiber non-woven fabric to deform or flow by melting so as to achieve the desired degree of adhesion between the components of the group, without affecting in a way adverse, for example, to deform and / or cause the rest of the supported fibrous tissue group to fuse. Generally, the desired pressure can be applied for about 1-60 seconds, preferably for about 1-30 seconds.

Care should be taken to ensure that the applied pressure is not developed in a way that adversely affects the supported fibrous tissue group. Also, pressure should not be applied to the supported fibrous fabric assembly which would make the multi-component fiber non-woven fabric non-porous or so adversely affect the absorption and flow properties of fluid through the multi-component fiber non-woven fabric (flow lateral and / or vertical) in a significant way, although in some cases it may be desired to purposely make a portion of the non-woven fabric of multicomponent fibers non-porous, i.e. impermeable to fluid flow, so as to, for example, control the flow of fluid . Such an approach is particularly useful in the impermeable joining of the edges of the supported fibrous tissue assembly so as to avoid fluid leaks and direct the fluid flow to a desirable outlet.

The supported fibrous tissue group is desirably prepared so that the group exhibits sufficiently high permeability and adhesion characteristics. In particular, the supported fibrous fabric group preferably has a water flow rate of at least about 50%, more preferably at least about 70%, and more preferably at least about 90%, of the water flow rate of the multicomponent fiber non-woven fabric to be alone and / or the water flow rate of the second fibrous tissue (if present). The flow rate in water is the quantity of water per period of time per unit of pressure per unit of surface area of the group and is here expressed in terms of ml / min / kPa / m2. The flow rate in the water is measured, if possible, with the application of a pressure of 7 kPa, and all the flow rates in the water reported here reflect the measurement at this applied pressure.

Furthermore, the group of supported fibrous fabric preferably comprises a second fibrous fabric-non-woven fabric of multicomponent fibers and a non-woven fabric of multicomponent fibers-support material with a tear strength of at least 50 kg / m, more preferably at least about about 100 kg / m, and more preferably at least about 150 kg / m, when dry and, more preferably, also after immersion in water at 90 ° C for 30 minutes. The supported fibrous tissue group will ideally comprise a second multi-component fibrous fiber nonwoven fabric and a tear strength multi-component fiber nonwoven backing material that is sufficiently high to cause the supported fibrous fabric group to fail. can be torn without destroying the second fibrous tissue and / or support material.

The supported fibrous tissue group of the present invention desirably exhibits a stiffness in bending (ASTM D 1388-64) of at least 10 times, preferably at least 50 times, more preferably at least 100 times, for example, about 500 times or more, and more preferably at least about 1000 times, the flexural stiffness of the multicomponent fiber non-woven fabric and the second fibrous fabric (if any).

The supported fibrous tissue group of the present invention can preferably withstand shear strain rates, such as those encountered in dynamic filtration, equal to at least about 200,000 sec'1, preferably at least about 400,000 sec-1, and more preferably at least equal to about 500,000 sec-1. Similarly, the supported fibrous tissue group of the present invention can preferably withstand back pressure of at least about 100 kPa, preferably at least about 200 kPa, more preferably at least about 400 kPa, and more preferably at least about 500 kPa.

Employment procedures

The supported fibrous tissue assembly of the present invention can be used for any suitable purpose, for example, for any purpose for which a conventional supported fibrous group could be used. Since the supported fibrous tissue group of the present invention exhibits excellent adhesion characteristics while maintaining good permeability characteristics / the supported fibrous tissue group of the present invention can also be used in applications and environments where a fibrous tissue group may not be suitable supported conventional, such as in high shear or pulsed flow environments or in applications where the supported fibrous tissue assembly is subjected to high backflow pressures. The supported fibrous tissue assembly of the present invention is useful in cross flow filtration devices and applications and particularly suitable for dynamic filtration devices and applications, especially those requiring vibrating and rotating dynamic filtration devices.

Thus, the present invention provides a filter element comprising a casing and a supported fibrous tissue assembly of the present invention. Such a filter element may include the supported fibrous tissue assembly of the present invention in any suitable configuration, which includes, for example, in a sheet form in which the backing material is a plate, a pleated configuration in which the support is a mesh, or tubular configuration in which the support material is a tube. The present invention also provides a method for filtering a fluid, which method comprises passing a fluid through the supported fibrous tissue assembly of the present invention.

Examples

The following examples further illustrate the present invention and, of course, should not be construed as limiting its scope in any way.

Example 1

This example illustrates the superior permeability and adhesion characteristics of the supported fibrous tissue group of the present invention.

In particular, the permeability of a single-component fibrous non-woven fabric alone (sample 1A), of a single-component fibrous non-woven fabric coupled but not joined to a stainless steel support (sample 1B), of a fabric was measured multicomponent fibrous non-woven fabric alone (sample 1C), of the multicomponent fibrous non-woven fabric coupled but not joined to the stainless steel support (sample 1D), of the multicomponent fibrous non-woven fabric coupled and joined to the stainless steel support (sample 1E), of the single component fibrous non-woven fabric coupled but not joined to the stainless steel support with the multicomponent fibrous non-woven fabric between them (sample 1F), and of the single component fibrous non-woven fabric joined to the stainless steel support with the fabric multi-component fibrous non-woven fabric included between them (1G samples). The tear strengths of the various linked embodiments were also determined, as far as applicable.

The single component fibrous nonwoven fabric used in this series of experiments was Reemay® 2016 (Snow Filtration Co. Cincinnati, Ohio). The nonwoven fabric had a sheet weight of approximately 46g / m2 and was a randomly oriented fibrous nonwoven fabric made of joined flocks of 100% polyester fibers. The thickness of the non-woven fabric was approximately 229 μm (ASTM test procedure D 1777-64 (reapproved in 1975)), while the air permeability of the fabric was approximately 274300 lpm / m2 (ASTM test procedure of 737 -75). The tensile strength of the non-woven fabric was approximately 661 kg / linear m along the machine direction and approximately 482 kg / linear m in the transverse machine direction (ASTM D 1117-77 test procedure).

The stainless steel support was a 304 stainless steel plate approximately 305 μm thick and having chemically etched holes approximately 380 μm in diameter. These holes, through which the permeate was extracted, were approximately 900 μm from the center, thus providing an opening area of approximately 16% for permeation. The surface of the stainless steel plate was chemically roughened when etching the holes, which improved the joint. The surface of the plate was also made more conducive to joining by exposing the plate to approximately 370 ° C for approximately one hour in an oven.

The multicomponent fibrous nonwoven fabric that was used in this series of experiments was Celbond® T105 (Hoechst-Celanese, Salisbury, North Carolina). The T105 nonwoven fabric comprised 100% concentric oriented bicomponent fibers featuring a linear low density polyethylene cover with a melting point of 127 ° C and a polyester core with a melting point of 256 ° C. T105 nonwoven fabric had a sheet weight of approximately 68g / m2 and was a randomly oriented, wet spread fibrous nonwoven fabric composed of fibers approximately 20 μm diameter x 1.27 cm length, Celbond® T105 . The thickness of the T105 non-woven fabric was approximately 406μm (test procedure ASTM D 1777-64), while the air permeability of the fabric was approximately 167600 lpm / m2 (test procedure ASTM D 737-75). The tensile strength of the T105 non-woven fabric was approximately 107 kg / linear m along the machine direction and approximately 71 kg / linear m in the transverse machine direction (ASTM D 1117-77 test procedure).

The filtrate flow was determined by measuring the flow of deionized water at room temperature (for example, about 20-25 ° C), with applied pressure of about 7 kPa. The flow rate of water through the single component nonwoven fabric was approximately 425 lpm / m2 or approximately 62 lpm / m2 / kPa. The permeability of a particular group incorporating the single component fibrous nonwoven fabric was calculated by determining the flow rate in water with an applied pressure on the group of approximately 7 kPa and dividing that flow rate by the flow through the membrane alone (i.e., approximately 425 lpm / m2 or about 62 lpm / m2 / kPa) to obtain a percentage permeability. Similarly, the water flow rate through the multicomponent fibrous nonwoven fabric alone was approximately 436 lpm / m2 or about 63 lpm / m2 / kPa. The permeability of a particular group incorporating the multicomponent fibrous nonwoven fabric, in the absence of the single single component fibrous nonwoven fabric, was calculated by determining the flow rate in water at an applied pressure of approximately 7 kPa across the group and dividing that flow rate for the flow through the membrane alone (i.e., about 436 lpm / m2 or about 63 lpm / m2 / kPa) to obtain a percentage permeability.

The splicing of the single component fibrous nonwoven fabric (fabric), multicomponent fibrous nonwoven fabric (interlayer), and / or the stainless steel plate (backing) was accomplished by use of a laminator. The supported fibrous tissue assembly was adequately stretched as a whole and then fed to the laminator, which included an upper and lower heated conveyor belt through which the assembly was passed. The temperature of the webs was adjusted to 160-170 ° C, i.e., higher than the melting temperature of the components of the two-component fiber cover and lower than the melting temperature of the core components of the two-component fibers, as well as of the fibrous non-woven fabric. single component and support of stainless steel. The distance between the two belts, referred to as the belt height was 0.9 mm, was adjusted approximately to the thickness of the unjoined assembly so as to uniformly heat the assembly prior to applying interstice pressure. Thermal equilibrium was achieved as the assembly moved along the heated conveyor belts, with the dwell time before the application of a gap pressure (which is determined by the speed of the conveyor belts) of approximately 60 seconds. The gap between the upper conveyor belt and the roller, i.e., the height of the interstice, was 0.6 ram, and the pressure of the interstice roller was either about 21 kPa (for sample 1E) or about 186 kPa ( for sample 1G). After exiting the interstice roller, the supported fibrous tissue assembly was allowed to cool to room temperature.

The tear strength between the two adhered layers was determined according to ASTM D 2724-79 by tearing the two layers from each other in opposite directions at an angle of 180 °. Tear strength, for the purpose of defining the supported fibrous tissue group of the present invention, is the load required to tear one of the two layers adhered to the other layer (which is fixed) at a speed of 5.08 cm / minute at a constant rate of elongation within a 2.54 cm wide and 10.16 cm long strip of the adhered sheets. The tear strength of the adhered sheets was also determined after immersion of each test strip in water at 90 ° C for 30 minutes.

Table 1 lists the junction conditions and physical characteristics of the various groups evaluated in these experiments.

As is clear from the data listed in Table 1, the supported fibrous tissue group of the present invention exhibits excellent permeability and adhesion characteristics. In particular, the supported fibrous tissue group of the present invention (as exemplified by samples 1E and 1G) maintains a significant portion of the permeability of the non-joined group (as exemplified by samples 1D and 1F, respectively), and also of the fibrous non-woven tissues. single-component multicomponent alone (as exemplified by samples 1A and 1C, respectively), while having excellent adhesion characteristics as evidenced by the tear strength values. However, the existence of a multicomponent fibrous nonwoven fabric has a small adverse effect on permeability as illustrated by a comparison of the permeabilities of the supported fibrous tissue groups of the present invention comprising the multi-component and single fibrous nonwoven fabrics with steel backing. stainless steel (as exemplified by sample 1G) and the single component fibrous nonwoven fabric and stainless steel support alone (as exemplified by sample 1B).

The supported fibrous tissue groups (as exemplified by samples 1E and 1G) exhibited excellent wet and dry tear strength characteristics as between the multi-component fibrous nonwoven and the stainless steel support. The supported nonwoven group (as exemplified by sample 1G) also exhibited good dry and wet tear strength characteristics as between multicomponent fibrous nonwoven and single component fibrous nonwoven. Example 2

This example illustrates the low permeability characteristics of a group of supported fibrous tissue prepared in a similar manner to that of Example 1, except for the use of a single component fibrous nonwoven as an interlayer between the fibrous nonwoven. single component and the stainless steel support described in Example 1, contrary to the dictates of the present invention.

A group of supported fibrous tissue similar to those of Example 1 was prepared using the laminator (except for a crevice pressure of about 186 kPa) for making the junction of the single component fibrous non-woven fabric (cloth) of the Example 1, a single component fibrous nonwoven fabric having a lower melting temperature (interlayer), and the stainless steel plate (support) of Example 1. The single component fibrous nonwoven interlayer was polypropylene and was commercially available as Typar® T135 (Midwest Filtration Company, Hamilton ,, Ohio). The single component fibrous nonwoven interlayer had a weight of about 31 g / mz and was a joined flock fibrous nonwoven fabric composed of fibers having an average diameter of about 23 μm. The thickness of the single component fibrous nonwoven interlayer was approximately 254 μm (ASTM D test procedure 77-64), while the air permeability of the fabric was approximately 76200 lpm / m2 (ASTM D test procedure D 737-75). The tensile strength of the single component nonwoven interlayer was about 482 kg / linear m in the machine direction and about 268 kg / linear m in the cross-machine direction (ASTM D 1117-77 test procedure).

The permeability and tear strength of the group were measured as described in the same way as described in Example 1, and the resulting values are listed in Table 2. For comparison purposes, the same group was similarly tested in unjoined form , and these resulting values are also listed in Table 2. In particular, the filtrate flow was determined by measuring the flow of deionized water at room temperature (for example, about 20-25 ° C) at an applied pressure of about 7 kPa. The water flow through the unjoined group was approximately 425 lpm / m2 or approximately 62 lpm / m2 / kPa. The permeability of the joint unit was calculated by determining the flow rate in water at an applied pressure of approximately 7 kPa across the unit and dividing that flow rate by the flow through the membrane alone (i.e., approximately 425 lpm / m2 or approximately 62 lpm / m2 / kPa) to obtain a percentage permeability.

As is clear from the data listed in Table 2, while the supported fibrous fabric group using a single component non-woven fiber interlayer exhibited good tear strength characteristics, this group exhibited very low permeability characteristics. However in this particular comparative example, there was no significant permeability. Although single component fibers consisted of polypropylene, the same results are expected for other single component fibers such as polyethylene which has a lower melting temperature than polypropylene.

Example 3

This example illustrates the good permeability and adhesion characteristics of another embodiment of the supported fibrous tissue group of the present invention, in particular a supported fibrous tissue group similar to those of Example 1 except for the use of a single component fibrous woven fabric, rather than a non-woven fabric, together with a stainless steel plate and a multi-component fibrous non-woven fabric interlayer.

A group of supported fibrous tissue similar to that of Example 1 was prepared using the laminator (except for the need for a dwell time of approximately 300 seconds before applying a crevice pressure of approximately 186 kPa) to achieve the splice of the single component fibrous woven fabric (cloth), the multicomponent fibrous nonwoven fabric (interlayer) of Example 1, and the stainless steel plate (carrier) of Example 1. The single component fibrous woven fabric was polyester and is commercially available as PeCap® 7-5 / 2 (Tetko, Ine., Briarcliff Manor, New York). The single component fibrous woven fabric cloth had a sheet weight of approximately 64 g / m2 and was an upper and lower square woven weave composed of fibers having an average diameter of approximately 33 μm. The thickness of the single component woven fabric cloth was approximately 65 μιη, while the mesh opening was approximately 5 µm, with an open area of 2%.

The permeability and tear strength of the group were measured as described in the same way as described in Example 1, and the resulting values are listed below in Table 3. For comparison purposes, the same group in unjoined form was tested in a similar way, and these resulting values are also listed in table 3. In particular, the filtrate flow was determined by measuring the flow of deionized water at room temperature (for example, about 20-25 ° C) with applied pressure of about 7 kPa. The water flow through the unjoined group was approximately 230 lpm / m2 or approximately 33 lpm / m2 / kPa. The permeability of the joint unit was calculated by determining the flow rate in water at an applied pressure of approximately 7 kPa across the unit and dividing that flow rate by the flow through the membrane alone (i.e., approximately 230 lpm / m2 or approximately 33 lpm / m2 / kPa) to obtain a percentage permeability.

As is clear from the data listed in Table 3, the supported fibrous tissue group of the present invention using a fibrous woven tissue, rather than a fibrous non-woven tissue, exhibited satisfactory permeability and adhesion characteristics.

Example 4

This example further illustrates the satisfactory permeability and adhesion characteristics of an embodiment of the supported fibrous tissue assembly of the present invention under unfavorable filtration conditions.

The supported fibrous tissue assembly of the present invention of example 3 (namely, sample 3B) was installed in a conventional filter housing. A hot water suspension containing dissolved sugar and various fibrous and biological debris was pumped through the supported fibrous tissue group or for the purpose of dehydrating the fluid. Filtration was carried out at a feed pressure of about 69 kPa and a feed temperature of about 50-70 ° C. Furthermore, the group of supported fibrous tissue was made to oscillate at about 40 Hz around a vertical axis and, with width of about 2.54 cm, to enhance the permeating flow. During filtration, fibrous and biological debris was rejected by the supported fibrous tissue group, thereby causing fluid with significantly lower turbidity to permeate the group. After 4 hours of filtration there was no indication of delamination. Thus, the supported tissue assembly of the present invention remains whole even after prolonged exposure to fluids at high pressure, temperature and shear shear.

All citations provided herein are incorporated herein in their entirety by reference.

While this invention has been described with emphasis on preferred embodiments, it will become clear to those of ordinary skill in the art that variations of the preferred embodiments may be utilized and it is understood that the invention may be practiced otherwise than specifically. described here. Accordingly, this invention includes all modifications embodied in the spirit and scope of the invention as defined by the following claims.

Claims (20)

CLAIMS 1. A group of supported fibrous fabric comprising a support material which adheres to a non-woven fabric of multicomponent fibers comprising a first polymer and a second polymer such that said second polymer is present on at least a portion of the surface of said multicomponent fibers and has a softening temperature lower than the softening temperatures of said first polymer and such support material, wherein said group of supported fibrous tissue group has a water flow rate equal to at least 20% of the water flow rate of said non woven fiber fabric multicomponent alone. The supported fibrous tissue group of claim 1, wherein said multi-component fibers comprise at least about 10% by weight of said first polymer and no more than about 90% by weight of said second polymer. The supported fibrous fabric group of claim 1 or 2, wherein the tear strength between such multicomponent fiber non-woven fabric and support material is at least about 50 kg / m. The supported fibrous tissue group of any one of claims 1-3, wherein said first and second polymers are polyolefins. The supported fibrous fabric group of claim 4, wherein said first polymer is polyester and said second polymer is polyethylene. The supported fibrous tissue group of any one of claims 1-5, wherein said multicomponent fibers comprise a core of said first polymer and a cover of said second polymer. The supported fibrous tissue group of any one of claims 1-6, wherein said support material has a bending stiffness equal to at least about 100 times the bending stiffness of such multi-component fiber nonwoven. The supported fibrous tissue group of any one of claims 1-7, wherein such support material is a metallic support material. The supported fibrous tissue group of any one of claims 1-8, wherein said supported fibrous tissue group has a water flow rate equal to at least about 50% of the water flow rate of such multicomponent fiber nonwoven fabric to be alone. The supported fibrous fabric group of claim 9, wherein said supported fibrous fabric group has a water flow rate of at least about 70% of the water flow rate of such multicomponent fiber nonwoven fabric alone. The supported fibrous fabric group of claim 10, wherein said supported fibrous fabric group has a water flow rate of at least about 90% of the water flow rate of such multicomponent fiber nonwoven fabric alone. The supported fibrous tissue group of any one of claims 1-11, wherein said supported fibrous tissue group further comprises a second fibrous tissue which adheres to such multicomponent fiber nonwoven such that said nonwoven fabric of multicomponent fibers is positioned between said second fibrous tissue and said support material, and in which said group of supported fibrous tissue has a water flow rate equal to at least about 20% of the water flow rate of said second fibrous tissue alone. The supported fibrous fabric group of claim 12, wherein the tear strengths between such multicomponent fiber nonwoven fabric and the backing material and between such multicomponent fiber nonwoven fabric and said fibrous fabric are at least about 50 kg / m. A method of filtering a fluid, which method comprises passing a fluid through the supported fibrous tissue assembly of any one of claims 1-13. A method of filtering a fluid, which method comprises passing a fluid through the supported fibrous tissue assembly of any one of claims 1-13 such that such nonwoven tissue is subjected to tangential deformation forces equal to at least about 200000 sec-1. A filter element comprising a shell and the supported fibrous tissue assembly of any one of claims 117. A process for preparing a supported fibrous tissue group, wherein such a process comprises (a) placing a multi-component fiber nonwoven fabric in contact with a support material to make a supported fibrous tissue group, in wherein such multi-component fibers comprise a first polymer and a second polymer such that the second polymer is present on at least a portion of the surface of the multi-component fibers and has a softening temperature lower than the softening temperatures of said first polymer and such support material , (b) subjecting such multi-component fiber nonwoven fabric to a temperature higher than the softening temperature of that second polymer and lower than the softening temperatures of that first polymer and such support material, and (c) applying pressure to that group of fibrous fabric supported while the non-woven fabric of multicomponent fibers are at a temperature above the softening temperature of the second polymer so that the support material adheres to this multicomponent fiber fabric, and this group of supported fibrous fabric has a flow rate in water of at least about 20% of the flow rate in water of multicomponent fiber non-woven fabric alone. 18. The process of claim 17, wherein said process further comprises placing such multi-component fiber nonwoven fabric between said support material and a second fibrous fabric, subjecting said multi-component fiber nonwoven fabric to a temperature above the temperature of softening of said first polymer, said second fibrous tissue, and said support material, and applying pressure to said group of supported fibrous tissue such while said multicomponent fiber non-woven fabric is at a temperature higher than the softening temperature of said second polymer in such that said support material and said second fibrous fabric adhere to said multicomponent fiber non-woven fabric, and said group of supported fibrous fabric has a water flow rate equal to at least 20% of the water flow rate of said fibrous fabric alone. 19. The process of claim 18, wherein said process further comprises subjecting such multi-component fiber nonwoven fabric to temperature and pressure sufficient to render a portion of such multi-component fiber nonwoven fabric impermeable to fluid flow. 20. The process of claim 19, wherein said group of supported fibrous fabric has edges and at least a portion of said edges constitutes a watertight seam by means of said impermeable portion of said multi-component fiber non-woven fabric.